The present invention relates to a printed circuit board.
A conventional printed circuit board 5 is shown in FIG. 7, and is produced by etching copper film 2 on a copper clad laminated plate 1 to form a desired circuit conductor 3 on the upper surface of a base plate 4.
On the circuit conductor 3 of the printed circuit board 5, an insulating paste film 6 is formed. Such a process is well known, and need not be described in detail.
However, such a conventional printed circuit board 5 of the above described construction has the disadvantage that heat produced during operation of the circuit conductor 3 can not be sufficiently dissipated owing to the insulating property of the paste film 6 which acts as effective electrical and thermal insulation to the circuit conductor 3. Consequently, the circuit conductor 3 may be overheated during use of the printed circuit board 5 to cause erroneous operation or short service life.
An object of the present invention is to eliminate or at least mitigate the above mentioned disadvantage, and to provide an improved printed circuit board which effectively prevents the circuit conductor from overheating.